1. Field of the Invention
This invention relates to siphons and particularly to siphons with moving plugs.
2. Description of the Prior Art
The hydrodynamic principle known as the siphon effect involves the transfer of a liquid by gravity from a source volume of the liquid to a receiving location at a lower elevation using a conduit having a one end immersed below the surface of the source volume, a peak located above the surface of said source volume, and a downstream end located at a level below the first end. As long as the conduit remains liquid-filled, and the hydrostatic head of the downstream arm exceeds the hydrostatic head of the upstream arm, water will flow out of the source volume. The siphon principle provides the advantage of removing water by gravity thus avoiding the need for a pump. The difficulty in establishing a siphon effect is in filling the conduit with the liquid. Several approaches for coping with this problem are disclosed in the prior art.
U.S. Pat. No. 958,415 teaches a simple siphon that uses a simple piston inside of the siphon tube to pull liquid from the contain into the siphon tube. This invention is simple and not useful in larger siphoning operation. U.S. Pat. No. 2,783,715 teaches a siphon that uses a cylinder that attaches to a siphon hose. Inside the cylinder is a piston that has packing at one end and a pyramid shaped plug at the other. This plug is screwed into a retainer. Openings are formed in the retainer structure that divert the liquid around the plug and out of the cylinder. The piston is pulled once or a few times, as needed, to get the flow going. This system is an improvement in that it can be used with longer hoses and larger type suction tubes. The use of the piston, however, still requires a piston with packing and the plug to ensure proper operation. U.S. Pat. No. 3,908,689 teaches another type of piston in a cylinder to initiate siphon flow. This device dispenses with the plug at the bottom of the chamber and replaces it with a system that requires the discharge end of the device be closed as the piston is operating. This is inconvenient if the discharge includes a long hose or is placed in a tank or other container. At best, two people are needed to properly operate such a system, making it inefficient and unproductive. U.S. Pat. No. 4,301,826 teaches yet another piston type siphon that has check valves, seals and packing to make the piston work effectively. U.S. Pat. No. 6,412,528 teaches a bellows type pump to start siphoning. This device also has two check valves as part of the pump portion. U.S. Pat. No. 6,412,528 teaches yet another vacuum type piston pump for siphoning. Unlike the other patents, this device uses a sealed container to draw the vacuum and has the siphon hose adjacent to the pump, rather than being in line with the pump. As in the other cases, this device requires, pumps, seals and check valves to operate. Finally, U.S. Pat. No. 6,926,026 teaches a different type of pump. In this design, there is a cylinder within a cylinder. The inner cylinder is hollow and has a check valve installed in the bottom and a hose fitting below the valve. The outer cylinder has a hose fitting at the top and a check valve under the hose fitting. The user inserts the device in line with hoses and begins the flow by manipulating the outer cylinder-moving it back and forth-to begin fluid flow. Although this device is simpler than the others, it still requires the use of check valves and a seal. Moreover, vigorous pumping of the cylinders might result in the two cylinders separating as there is nothing but the seal to keep the inner cylinder within the outer cylinder. Thus, there is a need for a simple siphoning device that dispenses with seals and check valves and yet quickly and easily begins the flow of liquid though the siphon.